Concentrations and Distribution of Manmade Organic Compounds in the Basin, Nevada and California, 1997-99

By Michael S. Lico and Nyle Pennington Water-Resources Investigations Report 99-4218, Version 1.1 Abstract baseflow conditions. Upper Angora Lake had the fewest number of organochlorine compounds detected of all lake The U.S. Geological Survey, in cooperation with samples. Dioxins and furans were not detected in SPMD the Tahoe Regional Planning Agency and the Lahontan samples from two sites in Lake Tahoe or from two tribu- Regional Water-Quality Control Board, sampled Lake tary streams. Tahoe, major tributary streams to Lake Tahoe, and several The number of polycyclic aromatic hydrocarbon other lakes in the Lake Tahoe Basin for manmade organic (PAH) compounds and their combined concentrations compounds during 1997-99. generally were higher in samples from Lake Tahoe than Gasoline components were found in all samples col- those from tributary streams. Areas of high-motorized lected from Lake Tahoe during the summer boating sea- boating activity at Lake Tahoe had the largest number and son. Methyl tert-butyl ether (MTBE), benzene, toluene, highest concentrations of PAH’s. PAH compounds were ethylbenzene, and xylenes (BTEX) were the commonly detected in samples from SPMD’s in four of six tributary detected compounds in these samples. Most samples from streams during spring runoff, all tributary streams during tributary streams and lakes with no motorized boating had baseflow conditions, and at all lake sites. The most com- no detectable concentrations of gasoline components. monly detected PAH’s in tributary streams during spring Motorized boating activity appears to be directly linked in runoff were phenanthrene, fluoranthene, pyrene, and space and time to the occurrence of these gasoline compo- chrysene, and during baseflow conditions were phenan- nents. Other sources of gasoline components to Lake threne, 1-methylphenanthrene, diethylnaphthalene, and Tahoe, such as the atmosphere, surface runoff, and sub- pyrene. , which has an urban area in surface flow, are minor compared to the input by motor- its drainage basin, had the largest number and highest ized boating. Water sampled from Lake Tahoe during combined concentration of PAH’s of all stream samples. mid-winter, when motorized boating activity is low, had no MTBE and only one sample had any detectable BTEX compounds. Soluble pesticides rarely were detected in water samples from the Lake Tahoe Basin. The only detectable concentrations of these compounds were in samples from Blackwood and Taylor Creeks collected during spring runoff. Concentrations found in these samples were low, in the 1 to 4 nanograms per liter range. Organochlorine compounds were detected in sam- ples collected from semipermeable membrane devices (SPMD’s) collected from Lake Tahoe, tributary streams, and Upper Angora Lake. In Lake Tahoe, SPMD samples collected offshore from urbanized areas contained the largest number and highest concentrations of organo- chlorine compounds. The most commonly detected organochlorine compounds were cis- and trans-chlor- dane, p,p’-DDE, and hexachlorobenzene. In tributary streams, SPMD samples collected during spring runoff Diver retrieving semipermeable membrane device from Lake generally had higher combined concentrations of Tahoe, near Glenbrook, Nev. Photograph by R.J. Hoffman, organochlorine compounds than those collected during U.S. Geological Survey, August 1998.

U.S. Department of the Interior—U.S. Geological Survey Abstract 1 regulations in the Tahoe Basin include prohibition of most two-stroke engines and controlling sediment, and thus nutrient, input into the lake. Increased urbanization and its associated activities may be an important contributor to the reduction of Lake Tahoe’s clarity. Pesticide and fertil- izer use, leaking underground fuel storage tanks, and atmospheric deposition can all be important sources of manmade compounds that could upset the natural ecolog- ical systems within the lake. Before 1997, little was known about the concentra- tions of manmade organic compounds in Lake Tahoe and its tributary streams. During 1997, the U.S. Geological Survey (USGS) in cooperation with the Tahoe Regional Planning Agency and the University of California, Davis, Tahoe Research Group (TRG) collected the first data doc- umenting the presence of the gasoline components ben- zene, toluene, ethylbenzene, xylenes, methyl tert-butyl ether (MTBE), and tert-amyl methyl ether (TAME) in the lake (Boughton and Lico, 1998). Every sample taken from Semipermeable membrane sampling device, Upper Angora Lake, Calif., July 1998. Photograph by K.J. Hill, Tahoe the lake during the summer months had detectable con- Regional Planning Agency. centrations of MTBE. The findings of this study (Bough- ton and Lico, 1998) prompted a more detailed Bottom-sediment from Lake Tahoe had detectable investigation, the results of which are reported herein. concentrations of p-cresol, a phenol, in all but one sample. A sample collected near Chambers Lodge contained phe- Purpose and Scope nol at an estimated concentration of 4 micrograms per kilogram (µg/kg). Bottom-sediment samples from tribu- This report documents the occurrence and distribu- tary streams had no detectable concentrations of orga- tion of selected manmade organic compounds in water nochlorine or PAH compounds. Several compounds were and bottom sediment from Lake Tahoe, its major tributar- detected in bottom sediment from Upper Angora Lake at ies, and other Lake Tahoe Basin lakes. Organic com- high concentrations. These compounds and their concen- pounds investigated during this study include gasoline trations were p,p’-DDD (10 µg/kg), p,p’-DDE (7.4 components (VOC’s), soluble pesticides, and semivolatile µg/kg), 2,6-dimethylnaphthalene (estimated at 190 compounds (including organochlorine compounds, µg/kg), pentachlorophenol (3,000 µg/kg), and p-cresol PAH’s, dioxins, and furans). Locations of sampling sites (4,400 µg/kg). are shown in figure 1. Ancillary data collected as part of this study can be found in a report by Preissler and others INTRODUCTION (1999, p. 508-520). The results of this study are docu- mented to provide a useful benchmark from which future Lake Tahoe is a high alpine lake renowned for its comparisons can be made. clear, deep waters and has been designated an Outstand- Lake Tahoe was sampled at 10 locations during ing National Resource Water. The lake is a destination for August 1998 for VOC’s and soluble pesticides. Samples outdoor sporting enthusiasts who visit the lake throughout for VOC’s were taken from Lake Tahoe at five sites during the year. Its proximity to the San Francisco Bay Area, January 1999. Semipermeable membrane sampling about 240 kilometers (km) to the west, and setting in the devices (SPMD’s) were deployed to sample hydrophobic make it one of the premier summer vaca- organic compounds at eight locations at Lake Tahoe tion spots in the country. In recent years, the clarity of (July-August 1998). Water samples were obtained from Lake Tahoe has been decreasing at a rate that will make it six tributary streams during spring runoff (May 1998) and a lake less extraordinary in appearance within the next 30 during baseflow (October 1998) conditions. SPMD’s years (Goldman and others, 1998). The cause of this loss were deployed in the tributary streams for two periods of clarity is due to increased algae populations within the of approximately 8 weeks each (May-June 1998 and lake. Scientists and regulators require more information November-December 1998) to sample the hydrophobic that would allow them to make appropriate decisions on organic compounds. Lists of analytes for the several remedial actions needed to reverse this trend. All sewage classes of compounds can be found in tables 1-4 and in effluent has been exported from the Lake Tahoe Basin the following reports—Connor and others (1998), since the mid-1970’s. Other more recently enacted Foreman and others (1995), Furlong and others (1996),

2 Concentrations and Distribution of Manmade Organic Compounds in the Lake Tahoe Basin, Nevada and California, 1997-99 and Zaugg and others (1995). In Upper Angora Lake, about 8 km southwest of Lake Tahoe, water samples were taken for VOC’s and soluble pesticides during August 120° 15' 120° 00' 1998, and hydrophobic organic compounds (using Third Truckee Creek 80 NEVADA SPMD’s) during July-August 1998. Bottom sediment 431 395 was collected for analysis of hydrophobic organic com- WASHOE pounds at seven sites from Lake Tahoe, six tributary 267 Incline streams, and Upper Angora Lake during August 1998. WashoeWashoe CARSON CreekCreek

River Lake 39° 15' Two other lakes, and Lower Echo Lake, 89 Incline 1s were sampled for VOC’s during August 1998. Upper PLACER 2 Village1 Kings Angora Lake has no motorized boats and nearby automo- Beach Marlette bile traffic is minor. Fallen Leaf and Lower Echo Lakes Truckee TahoeTahoe Lake SquawSquaw 28 City 3 ValleyValley have substantial boating traffic during the summer Ward 4 RANGE months. Analytical results of water samples collected Creek LakLakee TRG CARSON BuoBuoyy CITY during 1997 and reported by Boughton and Lico (1998) TTahoeahoe 5 50 are included in the discussion section of this report. Blackwood 2s 6 Creek Glenbrook Mid-LakMid-Lakee 7 HomeHomewoodwood 8 3s Creek Sample Collection and Analysis SIERRA 9 Glenbrook Chambers Lodge 4s Water samples for VOC’s were collected using methods described by Shelton (1997). A stainless-steel General 10 Creek sampler, described by Shelton (1997), was lowered to the ZephZephyryr DOUGLAS 39° 00' CoCoveve desired depth on a stainless-steel cable connected to a Emerald Bay 11 calibrated reel. The sampler contained four 40-milliliter 12 KivaKiva Stateline Beach 13 207 (mL) vials. Each vial was flushed with seven volumes of Cascade 14 Lake Edgewood 15 sample and the final 40 mL remained in the vial. EL DORADO 5s TahoeTahoe 6s Creek

TaylorTaylor KKeyseys Although this sampler was designed for suburban Fallen eek NEVADA

CrCreekeek CALIFORNIA Creek Leaf Cr Lake RiverRiver streams, its ability to allow sample vials to be purged out 16 r TTrout ensures the water sample in the vials is representative. Upper NEVADA 17 Angora Lake Trout Approximate flushing volumes at 3- and 30-meter (m) Creek 18 depths are 260 and 230 mL, respectively (R.J. Hoffman,

OREGON IDAHO ruckee Truckee Lower T ALPINE U.S. Geological Survey, written commun., 1999). Imme- 50 NEVADA Echo Lake Reno 89 diately upon retrieval and before opening, the sampler Area CALIFORNIA Woodfords of map Upper was placed in a preservation chamber (Shelton, 1994) to

Truckee UpperUpper Las 4 Vegas River minimize contamination of the samples by atmospheric 38° 45' 88 89 Los sources. Samples were removed from the sampler, pre- Angeles 0 5 KILOMETERS served with 1:1 hydrochloric acid, capped, placed on ice,

0 5 MILES and sent overnight to the USGS National Water Quality

Base from U.S. Geological Survey digital data, Laboratory (NWQL) in Arvada, Colo. VOC’s were ana- 1:24,000 and 1:100,000,1969-85. Universal Transverse Mercator projection, Zone 11 lyzed using gas chromatography-mass spectrometry as described by Connor and others (1998). Sampler perfor- EXPLANATION mance was documented by Halde and others (1999).

Boundary of Lake Tahoe Basin Quality-assurance samples for VOC’s included sampler Boundary of subbasin blanks (a measure of potential contamination by the sam- Tributary stream site, number, and pler) and ambient blanks (a measure of potential contam- type of data collected ination from the atmosphere). 1s VOC's, pesticides, SPMD, and bottom sediment Water samples for soluble pesticides were collected Lake site, number, and type of data collected using the same stainless-steel sampler used for VOC’s with the exception that no vials were in the sampler. 10 VOC's 4 VOC's, pesticides, and bottom sediment Water from the sampler was collected and composited 13 VOC's, pesticides, SPMD, and bottom in a 3-liter teflon bottle. The water sample was filtered sediment through a glass fiber filter, placed on ice, and sent over- night to the NWQL. Soluble pesticides (86 compounds) were extracted from water samples using solid-phase Figure 1. Lake and tributary stream sampling sites in Lake Tahoe Basin, Nevada and California. extraction procedures outlined by Sandstrom and others

INTRODUCTION 3 Table 1. Volatile organic compounds in water samples collected at Lake Tahoe, other nearby alpine lakes, and tributary streams, July 1997-January 1999 Table 1. Volatile organic compounds in water samples collected at Lake Tahoe, other nearby alpine lakes, and [Concentrationstributary streams, in micrograms July 1997-January per liter; <, less 1999—Continued than; --, not determined]

Site Depth Meta- Methyl tert- Tert-amyl Ethyl- Ortho- number (meters below Date Benzene 1 Toluene1 and para- butyl ether1 methyl ether1 benzene1 xylene1 (fig. 1) land surface) xylene1 (MTBE) (TAME) Lake Tahoe Samples 1 3 09/03/1997 E0.5 0.13 E0.02 E0.03 E0.09 0.45 E0.05 1 3 08/11/1998 .17 1.0 .24 .42 1.0 .84 .10 1 3 01/13/1999 <.10 <.05 <.03 <.064 <.064 <.17 <.11 2 3 09/03/1997 .13 .68 .12 .20 .52 1.7 .14 4 3 07/29/1997 .15 .58 E.09 .16 .42 1.5 E.09

4 3 08/02/1997 .33 1.9 .39 .60 1.6 4.2 .20 4 3 08/12/1998 .11 .56 .097 .17 .44 1.3 .15 5 30 07/29/1997 <.032 <.04 <.03 <.064 <.064 .19 E.02 5 3 08/02/1997 <.06 E.04 <.03 <.064 E.03 .59 E.04 5 10 08/02/1997 <.06 <.07 <.03 <.064 E.04 .61 <.11

5 30 08/02/1997 <.032 <.04 <.03 <.064 <.064 .26 <.11 5 3 08/11/1998 <.10 E.08 <.03 <.064 <.064 .45 <.11 5 30 08/11/1998 <.10 <.05 <.03 <.064 <.064 .22 <.11 5 3 01/13/1999 <.10 <.05 <.03 <.064 <.064 <.17 <.11 5 30 01/13/1999 <.10 <.05 <.03 <.064 <.064 <.17 <.11

6 3 09/03/1997 E.04 E.09 <.03 <.064 E.05 .42 E.05 6 30 09/03/1997 E.02 E.04 <.03 <.064 <.064 .18 <.11 7 3 09/02/1997 E.04 E.1 E.01 <.064 E.06 .30 E.04 7 3 08/11/1998 <.10 .27 E.06 .099 .26 .47 <.11 7 3 01/13/1999 <.10 <.05 <.03 <.064 <.064 <.17 <.11

8 3 09/02/1997 E.05 .15 E.02 E.04 E.1 .45 E.05 9 3 08/12/1998 <.10 .27 E.04 E.07 .19 .78 .13 10 3 09/02/1997 .15 .70 .12 .23 .52 1.0 .14 10 3 08/11/1998 .61 4.4 1.1 2.0 4.7 1.3 .17 10 3 01/13/1999 <.10 E.02 <.03 <.064 E.02 <.17 <.11

11 3 08/12/1998 .21 1.0 .18 .36 .94 2.4 .45 12 3 08/12/1998 .44 1.5 .20 .59 1.5 4.0 .85 13 3 09/02/1997 E.07 .26 E.04 E.06 E.2 .68 E.07 13 3 08/12/1998 .18 .91 .17 .28 .72 2.0 .34 13 3 01/13/1999 <.10 <.05 <.03 <.064 <.064 <.17 <.11 14 3 08/12/1998 .17 .78 .12 .23 .58 1.8 .34 Tributary Stream Samples 1s -- 05/13/1998 E.004 <.038 <.03 <.064 <.064 <.11 <.11 1s -- 10/27/1998 <.10 E.02 <.03 <.064 <.064 E.06 <.11 2s -- 05/121998 <.032 <.038 <.03 <.064 <.064 <.11 <.11 2s -- 10/27/1998 <.10 <.05 <.03 <.064 <.064 <.17 <.11 3s -- 05/13/1998 <.032 <.038 <.03 <.064 <.064 <.11 <.11

3s -- 10/28/1998 <.10 <.05 <.03 <.064 <.064 <.17 <.11 4s -- 05/12/1998 <.032 <.038 <.03 <.064 <.064 <.11 <.11 4s -- 10/27/1998 <.10 E.04 <.03 <.064 <.064 <.17 <.11 5s -- 05/13/1998 <.032 <.038 <.03 <.064 <.064 <.11 <.11 5s -- 10/28/1998 <.10 <.05 <.03 <.064 <.064 <.17 <.11

4 Concentrations and Distribution of Manmade Organic Compounds in the Lake Tahoe Basin, Nevada and California, 1997-99 Table 1. Volatile organic compounds in water samples collected at Lake Tahoe, other nearby alpine lakes, and tributary streams, July 1997-January 1999—Continued

Site Depth Meta- Methyl tert- Tert-amyl Ethyl- Ortho- number (meters below Date Benzene 1 Toluene1 and para- butyl ether1 methyl ether1 benzene1 xylene1 (fig. 1) land surface) xylene1 (MTBE) (TAME)

6s -- 05/13/1998 <0.032 <0.038 <0.03 <0.064 <0.064 <0.11 <0.11 6s -- 10/28/1998 <.10 E.01 <.03 <.064 <.064 <.17 <.11 Other Nearby Lake Samples 2 3 3 09/05/1997 <.032 <.04 <.03 <.064 <.064 <.11 <.11 3 9.1 09/05/1997 <.032 E.01 <.03 <.064 <.064 <.11 <.11 15 3 09/04/1997 <.032 E.04 <.03 <.064 E.02 <.11 <.11 15 15 09/04/1997 <.032 E.02 <.03 <.064 <.064 <.11 <.11 16 3 08/10/1998 <.10 .11 <.03 <.064 E.08 .78 .14

17 3 09/04/1997 <.032 E.02 <.03 <.064 <.064 <.11 <.11 17 10 09/04/1997 <.032 <.04 <.03 <.064 <.064 <.11 <.11 17 3 08/13/1998 <.10 <.054 <.03 <.064 <.064 <.17 <.11 17 6 08/13/1998 <.10 <.054 <.03 <.064 <.064 <.17 <.11 18 3 08/10/1998 .40 3.5 .71 1.1 1.5 7.7 2.2 1 When an “E” is reported, the compound has passed all criteria used to identify its presence, and only the concentration is estimated (Connor and others, 1998). 2 Lake sites 3 and 17 have no motorized boating activity. (1992) and Zaugg and others (1995) and then analyzed by spectrometry. Models exist to estimate water concentra- gas or high-performance liquid chromatography. Sampler tions of organic compounds from SPMD concentrations blanks were collected for quality-assurance purposes. (Huckins and others, 1993; Ellis and others, 1995). Bottom-sediment samples were collected and pro- cessed using protocols developed for the National Water- Acknowledgments Quality Assessment Program (Shelton and Capel, 1994). The authors acknowledge individuals and agencies Sediment samples were sent overnight to the NWQL. The that helped with this investigation. Jon Paul Kiel, Rita sediment samples were extracted and analyzed for orga- Whitney, and Kevin J. Hill, Tahoe Regional Planning nochlorine compounds (28 compounds), PAH’s (79 com- Agency, provided logistical support and assisted in the pounds), and PCB’s (total) by gas chromatography data-collection activities on Lake Tahoe and Upper (Foreman and others, 1995; Furlong and others, 1996). Angora Lake. Jim Hildinger of Angora Lakes Resort Sediment samples from two tributary streams and two provided boats for data collection on Upper Angora Lake. sites at Lake Tahoe were sent to a contract laboratory USGS personnel that assisted in data-collection activities for determination of dioxins and furans (25 compounds) were Kip K. Allander, Timothy G. Rowe, and Armando using methods described by U.S. Environmental R. Robledo. Special thanks are given to USGS divers Ray Protection Agency (1986). J. Hoffman and Cade R. Hoffman, who deployed and Detection of semivolatile compounds in water retrieved SPMD samplers in Lake Tahoe. Personnel at the is problematic because of their low concentrations and USGS National Water Quality Laboratory that provided transient nature. Semipermeable membrane devices analytical results include Brooke F. Connor, Mary C. (SPMD’s) were used to sample for these compounds in Noriega, Donna L. Rose, Sonja R. Abney, Lucinda K. the water column. SPMD’s are devices that contain tri- Murtagh, Jana L. Iverson, Dennis J. Markovchick, olein in a low-density polyethylene tube (Huckins and Dawn E. Hrinko, and Mary C. Olson. others, 1990). These devices are effective in sequestering dissolved organic compounds from water and are useful OCCURRENCE OF MANMADE ORGANIC in assessing their potential bioavailability (Bevans and COMPOUNDS others, 1996). For quality-assurance purposes, a blank (SPMD’s transported to the sampling sites and opened Water to the atmosphere at the sites) was collected during each round of SPMD deployment. Compounds are recovered During the summers of 1997 and 1998, water from the SPMD’s by dialysis and gel-permeation chroma- samples from 13 sites in Lake Tahoe were collected and tography and analyzed by gas chromatography-mass analyzed for gasoline components (table 1). All summer

OCCURRENCE OF MANMADE ORGANIC COMPOUNDS 5 samples from Lake Tahoe had detectable concentrations not detected in these samples. Toluene and meta-and para- of the oxygenate MTBE and most samples had measur- xylene were detected in a sample from Zephyr Cove (site able concentrations of BTEX (benzene, toluene, ethyl- 10) at estimated concentrations of 0.02 and 0.02 µg/L, benzene, and xylene) compounds (table 2). MTBE respectively. concentrations ranged from 0.18 to 4.2 micrograms per Water samples collected from six tributaries to Lake liter (µg/L), with the highest concentrations found in sam- Tahoe had only a few detections of manmade organic ples from near Tahoe City (site 4) and in Emerald Bay compounds (tables 1 and 3). During spring runoff, ben- (site 12). Another gasoline oxygenate, TAME, was found zene was detected in a sample from Incline Creek (site 1s) in 19 of 25 samples at concentrations as great as 0.85 µg/L at an estimated concentration of 0.004 µg/L. Two pesti- (in Emerald Bay). One other gasoline oxygenate, ethyl cides were detected in a sample from Blackwood Creek tert-butyl ether (ETBE), was not detected in any sample at (site 2s)—simazine estimated at 0.0038 µg/L and atrazine a reporting level of 0.11 µg/L. BTEX compounds were estimated at 0.0031 µg/L. One pesticide was detected in a detected in 88 percent of the samples collected from Lake sample from Taylor Creek (site 5s)—DCPA estimated at Tahoe. The highest concentrations of BTEX compounds 0.0012 µg/L. During the fall baseflow period, VOC’s were measured in samples collected from Zephyr Cove were detected at low concentrations in three samples. Tol- (site 10), Emerald Bay (site 12), and near Tahoe City (site uene was detected at estimated concentrations of 0.01, 4). The most commonly detected BTEX compound was 0.02, and 0.04 µg/L in the Upper Truckee River (site 6s), toluene (found in 84 percent of the samples) with a maxi- Incline Creek (site 1s), and General Creek (site 4s), mum concentration of 4.4 µg/L found in a sample from respectively. MTBE was detected in a sample from Zephyr Cove. Benzene was detected in 68 percent of the Incline Creek at an estimated concentration of 0.06 µg/L. samples collected and the maximum concentration (0.61 No pesticides were detected in water samples collected µg/L) was in a sample from Zephyr Cove. Ethylbenzene from tributary streams during baseflow conditions. was detected in 68 percent of the samples and had a max- imum concentration of 1.1 µg/L in a sample from Zephyr Other Tahoe Basin lakes sampled for gasoline com- Cove. Xylenes were detected in 64 percent (ortho isomer) ponents during this study were Lower Echo (site 18), and 80 percent (meta and para isomers) of the samples Fallen Leaf (site 16), Cascade (site 15), Marlette (site 3), and Upper Angora (site 17) Lakes. Of these lakes, Upper collected. The maximum concentration for total xylene Angora and Marlette Lakes have no motorized boating was 6.7 µg/L in a sample from Zephyr Cove. activity, Cascade Lake has limited motorized boating During January 1999, samples were collected from activity, and Lower Echo and Fallen Leaf Lakes have con- five locations (sites 1, 5, 7, 10, and 13) in Lake Tahoe and siderable motorized boating activity. Samples from Upper analyzed for the same gasoline components discussed Angora and Marlette Lakes had no detectable concentra- above. MTBE, TAME, and most BTEX compounds were tions of MTBE, ETBE, TAME, and BTEX compounds,

Table 2. Percent detection and concentration ranges of gasoline components in water samples from Lake Tahoe and other nearby lakes

[Concentrations in micrograms per liter. Abbreviations: E, estimated concentration 1; MTBE, methyl tert-butyl ether; TAME, tert-amyl methyl ether]

Lake Tahoe Other nearby lakes 2

Concentration range Concentration range Percent detection Percent detection Compound of detection of detection

Motorized No motorized Motorized No motorized Summer Winter Summer Winter boats boats boats boats Benzene 68 0 E0.02-0.61 -- 25 0 0.40 -- Toluene 84 17 E0.02-4.4 E0.02 100 33 E0.02-3.5 E0.01-E0.02 Ethylbenzene 68 0 E0.01-1.1 -- 25 0 0.71 -- Ortho-xylene 64 0 E0.03-2.0 -- 25 0 1.1 -- Meta- and para-xylenes 80 17 E0.03-4.7 E0.02 75 0 E0.02-1.5 -- MTBE 100 0 0.18-4.2 -- 50 0 0.78-7.7 -- TAME 76 0 E0.02-0.85 -- 50 0 0.14-2.2 --

1 When an “E” is reported, the compound has passed all criteria used to identify its presence, and only the concentration is estimated (Connor and others, 1998).

2 Categories represent motorized boats, all types of motorized boats are allowed on the lakes; and no motorized boats, no motorized boats are allowed on the lakes.

6 Concentrations and Distribution of Manmade Organic Compounds in the Lake Tahoe Basin, Nevada and California, 1997-99 Table 3. Soluble pesticides in water samples and semivolatile organic compounds in semipermeable membrane sampling devices detected in tributaries to Lake Tahoe, Nevada and California

Compounds detected Site Soluble pesticides (fig. 1) (concentrations in Semivolatile compounds micrograms per liter) 1s Incline Creek Spring Runoffrunoff none detected cis-and trans-chlordane, chrysene, fluoranthene, hexachlorobenzene, pentachloroanisole, phenanthrene, pyrene Baseflow none detected trans-chlordane, p,p’-DDE 2s Blackwood Creek Spring runoff simazine (E0.0038 1), none detected atrazine (E0.0031) Baseflow none detected trans-chlordane, p,p’-DDE 3s Glenbrook Creek Spring Runoffrunoff none detected cis- and trans-chlordane, chrysene, fluoranthene, 1-methylpyrene, pyrene Baseflow none detected trans-chlordane 4s General Creek Spring runoff none detected cis-and trans-chlordane, fluoranthene, 4,5-methylpyrene, pentachoroanisole, phenanthrene Baseflow none detected trans-chlordane 5s Taylor Creek Spring runoffRunoff DCPA (E0.0012) cis- and trans-chlordane, p,p’-DDE, fluoranthene, benzo (g,h,i) perylene Baseflow none detected trans-chlordane, p,p’-DDE, pentachloroanisole 6s Upper Truckee River Spring runoff none detected cis- and trans-chlordane, pentachoroanisole Baseflow none detected cis- and trans-chlordane, p,p’-DDE, 1,6-dimethylnaphthalene, naphthalene

1 When an “E” is reported, the compound has passed all criteria used to identify its presence, and only the concentration is estimated (Connor and others, 1998). with the exception of an estimated toluene concentration Among the most commonly detected classes of of 0.01 µg/L in a sample from Marlette Lake and an esti- semivolatile organic compounds were organochlorines, mated concentration of 0.02 µg/L in a sample from Upper polycyclic aromatic hydrocarbons (PAH’s), and phtha- Angora Lake (table 1). An equipment blank from this lates. Organochlorine compounds were detected in sam- sample period also contained toluene at an estimated con- ples from all sites in Lake Tahoe and Upper Angora Lake (table 4). Samples from near Incline Beach (site 1), centration of 0.04 µg/L; thus, these values may be from Chambers Lodge (site 9), near Edgewood Creek (site 11), contamination of the sampler. Lower Echo Lake had the and Tahoe Keys (site 13) had the greatest number of com- highest measured MTBE and TAME concentrations pounds and the highest combined concentration of orga- found during this study. MTBE concentration was 7.7 nochlorine compounds (fig. 2). Upper Angora Lake (site µg/L and TAME concentration was 2.2 µg/L. BTEX com- 17) had the fewest number of organochlorine compounds pounds were found at the following concentrations in and was among the lowest combined concentration, as Lower Echo Lake: benzene, 0.40 µg/L; toluene, 3.5 µg/L; were samples from the TRG buoy (site 5), near Glenbrook ethylbenzene, 0.71 µg/L; ortho-xylene, 1.1 µg/L; and (site 7), near Chambers Lodge (site 9), and near Kiva meta- and para-xylenes, 1.5 µg/L. Fallen Leaf Lake had Beach (site 14). Trans- and cis-chlordane and p,p’-DDE detectable concentrations of MTBE (0.78 µg/L), TAME were detected in all samples from Lake Tahoe. Hexachlo- robenzene was detected at four Lake Tahoe sites and had (0.14 µg/L), toluene (0.11 µg/L), and meta- and para- the highest concentration in samples from near Incline xylene (estimated 0.08 µg/L). Beach and near Edgewood Creek. Water samples were collected from eight sites in PAH’s were detected in samples from all locations Lake Tahoe and two depths from Upper Angora Lake for sampled at Lake Tahoe and Upper Angora Lake (site 17). soluble pesticide analysis. Soluble pesticides were not The number of compounds detected ranged from a low detected in any sample from Lake Tahoe or Upper Angora value of 3 (Upper Angora Lake) to an upper value of 23 Lake. (near Kiva Beach, site 14). Samples taken near Incline

OCCURRENCE OF MANMADE ORGANIC COMPOUNDS 7 1,000 (site 4s) had the highest combined concentration of PAH’s during the spring runoff period. The most commonly 23 detected PAH’s were phenanthrene, fluoranthene, pyrene, 19 15 and chrysene. During baseflow conditions, PAH’s were 15 15 detected in samples from all six tributary streams. The 100 15 11 greatest number of compounds and highest combined 5 concentration were found in samples from Upper Truckee 5 River. Taylor, Blackwood, and General Creeks had the 5 6 4 6 lowest number of compounds and combined concentra- 10 4 tion. Phenanthrene was detected in samples from all 3 3 3 3 3 tributary streams. Other commonly detected PAH’s were 2 COMBINED CONCENTRATION,

IN MICROGRAMS PER KILOGRAM IN MICROGRAMS 1-methylphenanthrene, diethylnaphthalene, and pyrene. Dioxins and furans were analyzed in samples col- 1 lected from Upper Truckee River (site 6s) and Incline 155 7 91113 1417 3 METER 36 METER Creek (site 1s) and in Lake Tahoe near Edgewood Creek SITE NUMBER (site 11) and near Incline Beach (site 1). No dioxins or furans were detected in any of these samples. EXPLANATION 3 Number of compounds detected Organochlorines Bottom Sediment PAH's Bottom sediment was collected from seven sites at Figure 2. Number and combined concentration of semivolatile organic compounds (organochlorine and polycyclic aromatic Lake Tahoe, six tributary streams, and one site at Upper hydrocarbon compounds) detected in samples from semiper- Angora Lake during the summer of 1998 (fig. 1). These meable membrane devices placed in Lake Tahoe and Upper sediment samples were analyzed for semivolatile com- Angora Lake, July-August 1998. Sites are shown in figure 1. pounds (organochlorines, PAH’s, PCBs, and phenol), and Site 17 (Upper Angora Lake) is the only lake sampled for semi- volatile organic compounds that has no motorized boating for two samples, dioxins and furans. Bottom-sediment activity. samples from Lake Tahoe had few detectable manmade organic compounds. One compound, p-cresol, was found Beach (site 1), near Edgewood Creek (site 11), Glenbrook in all Lake Tahoe bottom-sediment samples except from (site 7), and Chambers Lodge (site 9) had high numbers near Incline Beach (site 1). Concentrations of p-cresol and large combined concentration of PAH’s (fig. 2). Sam- ranged from an estimated value of 17 µg/kg near Tahoe ple sites with low combined concentrations of PAH’s City (site 4) to 140 µg/kg near Glenbrook (site 7). were Upper Angora Lake and both depths at the TRG 10 buoy (site 5). The most commonly detected compounds were 9H-fluorene, fluoranthene, 1-methylphenanthrene, 5 3 3 3 3 acridine, and 1-methyl-9H-fluorene. 3 The number and combined concentration of orga- 3 2 nochlorine compounds in the tributaries were greatest in 2 Incline Creek (site 1s), General Creek (site 4s), Taylor 2 1 Creek (site 5s), and Upper Truckee River (site 6s) during 1 spring runoff (fig. 3). The most commonly detected orga- 1 nochlorine compounds were cis- and trans-chlordane, 0.5 pentachloroanisole, and hexachlorobenzene (table 4). 0.3

During baseflow conditions, Taylor Creek, Upper Truc- COMBINED CONCENTRATION, 1 kee River, and Incline Creek had the greatest number and PER KILOGRAM IN MICROGRAMS combined concentration of organochlorine compounds. 0.1 NO DETECTION 1s 2s 3s 4s 5s 6s Trans-chlordane and p,p’-DDE were the most commonly SITE NUMBER detected compounds during baseflow conditions. Con- centrations were generally higher during the spring runoff EXPLANATION 3 Number of organochlorine compounds detected than the baseflow-sampling period (fig. 4). During spring Spring snowmelt runoff, May-June 1998 runoff, PAH’s were detected in four of the six tributary Fall baseflow, November-December 1998 streams. Concentrations of PAH’s from Blackwood Creek (site 2s) and Upper Truckee River (site 6s) were below Figure 3. Number and combined concentration of organochlo- rine compounds detected in semipermeable membrane devices detectable levels. Incline (site 1s) and Glenbrook (site 3s) placed in Lake Tahoe Basin streams during spring snowmelt Creeks had the greatest number and combined concentra- runoff (May-June 1998) and fall baseflow (November-Decem- tion of PAH’s during this period (fig. 4). General Creek ber 1998) periods. Site locations are shown in figure 1.

8 Concentrations and Distribution of Manmade Organic Compounds in the Lake Tahoe Basin, Nevada and California, 1997-99 Table 4. Concentrations of semivolatile organic compounds in Lake Tahoe and Upper Angora Lake. Concentrations were determined on extracts from semipermeable membrane sampling devices. Site numbers correspond to those in figure 1.

[Concentrations in micrograms per kilogram of lipid; all concentrations are estimated. Abbreviations: m, meter; <, less than]

Site 1 Site 5 Site 5 Site 7 Site 9 Site 11 Site 13 Site 14 Site 17 Compound Blank (3 m) (3 m) (36 m) (3 m) (3 m) (3 m) (3 m) (3 m) (3 m) Acenaphthalene 6 <100 <100 5 5 <100 5 6 <100 <100 Acenapthene <100 <100 <100 <100 <100 <100 <100 18 <100 12 Acridine 29 24 <100 24 26 32 24 25 <100 <100 Anthracene <100 <100 <100 <100 <100 <100 <100 18 <100 <100

Benz(a)anthracene <100 <100 <100 <100 <100 <100 <100 11 <100 <100 Benzo(b)fluoranthene 28 <100 <100 <100 23 25 <100 24 <100 <100 Benzo(k)fluoranthene 2 <100 <100 <100 <100 .7 <100 2 <100 <100 Benzo(g,h,i)perylene 10 <100 <100 <100 <100 <100 <100 8 <100 <100 9H-Carbazole <100 <100 <100 <100 16 <100 <100 <100 <100 <100

Chrysene <100 <100 <100 <100 <100 <100 <100 4 <100 <100 Fluoranthene 41 24 26 27 35 47 24 94 24 23 9H-Fluorene 4 1 1 2 2 3 2 11 1 <100 1-methyl-9H-Fluorene 11 8 <100 8 9 11 9 11 <100 <100 Indeno(1,2,3-cd)pyrene 20 <100 <100 17 17 18 <100 16 <100 <100

Naphthalene 11 4 6 6 6 6 6 11 4 7 1,2-dimethylnaphthalene 5 <100 <100 3 <100 <100 <100 4 <100 <100 1,6-dimethylnaphthalene 14 <100 <100 10 <100 11 10 12 <100 <100 2,6-dimethylnaphthalene 8 <100 <100 6 6 6 5 6 <100 <100 2-ethylnaphthalene 15 <100 <100 12 12 12 11 13 <100 <100

2,3,6-trimethylnaphthalene 4 <100 <100 .2 .8 7 .09 2 <100 <100 Phenanthrene 28 19 27 22 24 20 18 59 21 22 1-methylphenanthrene 27 24 24 24 25 26 24 29 26 23 4,5-methylenephenanthrene 9 <100 <100 2 4 7 3 14 <100 <100 Phenanthridine <100 <100 <100 22 <100 23 <100 <100 <100 <100

Phenol 13 13 13 14 13 12 13 15 13 13 Pyrene 30 23 24 23 24 24 22 44 23 23 Bis(2-ethylhexyl)phthalate 42 60 51 48 48 43 37 36 48 41 Diethylphthalate 20 22 29 32 33 14 20 23 24 30 Dimethylphthalate 8 <100 <100 <100 <100 <100 <100 <100 <100 7

Di-n-butylphthalate 24 28 29 27 27 25 24 24 24 25 Di-n-octylphthalate 23 24 <100 23 24 23 23 22 24 <100 Hexachlorobenzene 9.5 <5.0 <5.0 <5.0 1 5 1 <5.0 <5.0 <5.0 Cis-chlordane 2 2 1 3 2 2 4 2 2 <5.0

Trans-chlordane 2 2 2 2 2 2 3 2 2 <5.0 p,p'-DDE 1 .9 1 .9 1 .9 1 .8 <5.0 <5.0 Dieldrin <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 1 <5.0 <5.0 <5.0 trans-Nonachlor 1 <5.0 <5.0 <5.0 <5.0 <5.0 1 <5.0 <5.0 <5.0

OCCURRENCE OF MANMADE ORGANIC COMPOUNDS 9 100 Discussion of Results 3 7 4 4 Organic compounds detected in water- and bottom- sediment samples collected from Lake Tahoe Basin indi- 2 2 cate human activities have introduced potentially harmful compounds into the Basin. Even though the concentra- 3 tions of these compounds are low, their presence suggests 10 a need to monitor waters within the Lake Tahoe Basin for 2 manmade organic compounds to ensure no further degra- 1 dation of its waters.

1 Several lines of evidence suggest that most VOC’s COMBINED CONCENTRATION,

IN MICROGRAMS PER KILOGRAM IN MICROGRAMS detected in water samples from lakes in the Tahoe Basin are the result of motorized watercraft use in the lakes. NO DETECTION NO DETECTION 1 1s 2s 3s 4s 5s 6s • VOC’s were found in all water samples collected from lakes where motorized boating occurred SITE NUMBER (table 2). EXPLANATION • Areas of high boating activity (Emerald Bay, 3 Number of PAH compounds Tahoe City, and Zephyr Cove in Lake Tahoe and Spring snowmelt runoff, May-June 1998 Fall baseflow, November-December 1998 Lower Echo Lake) had the highest concentra- tions of MTBE and BTEX compounds. Figure 4. Number and combined concentration of polycyclic aro- • Samples collected during periods of high boating matic hydrocarbon (PAH) compounds detected in the semiper- meable membrane devices placed in Lake Tahoe Basin streams activity (weekends during the summer), as during spring snowmelt runoff (May-June 1998) and fall baseflow reported by Boughton and Lico (1998), had some (November-December 1998) periods. Site locations are shown of the highest concentrations found in this study. in figure 1. • Water samples collected at open-water sites, where boating activity is light, had some of the Kiva Beach (site 14) had a concentration of p-cresol (110 lowest concentrations of MTBE and BTEX µg/kg). Several phthalate esters were detected in these found at Lake Tahoe during the boating season. samples and may be the result of contamination during • Water samples collected during the winter laboratory processing of the samples. Phenol was months, when boating activity is low, had no detected in a sample from near Chambers Lodge (site 9) detectable MTBE and minimal BTEX com- at an estimated concentration of 4 µg/kg. pounds (table 2). A phenol, p-cresol, was detected in bottom sedi- ment from Taylor Creek (site 5s) at an estimated concen- • No MTBE and minimal BTEX compounds were tration of 22 µg/kg. Several phthalate esters were detected found in lakes (Upper Angora and Marlette in all samples including the blanks and may be the result Lakes) where motorized watercrafts are prohib- of contamination during laboratory preparation of the ited. samples. Three dioxins were detected in a sample from The atmosphere, surface drainage of lands, and sub- Upper Truckee River (site 6s) at low concentrations. The surface drainage within the Lake Tahoe Basin are not the dioxins found were total heptachlorodibenzo-p-dioxin primary source of the high concentrations of VOC’s (5.8 ng/kg1), 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin observed in Lake Tahoe during the summer months. (2.5 ng/kg), and octochlorodibenzo-p-dioxin (22 ng/kg). Upper Angora and Marlette Lakes did not have any A sample from Incline Creek (site 1s) had octochloro- VOC’s present at concentrations greater than 0.02 µg/L. dibenzo-p-dioxin present at 5.2 ng/kg. This indicates that an atmospheric source for VOC’s in Several compounds were detected in bottom sedi- the Tahoe Basin is minor, if present at all. Tributary ment from Upper Angora Lake (site 17) at rather high streams sampled during spring runoff and baseflow concentrations. These compounds and their concentra- conditions only had a few detectable concentrations of tions were p,p’-DDD (10 µg/kg), p,p’-DDE (7.4 µg/kg), VOC’s, all less than 0.06 µg/L. This indicates that tribu- 2,6-dimethylnaphthalene (estimated at 190 µg/kg), pen- tary runoff within the basin is not a major source of tachlorophenol (3,000 µg/kg), and p-cresol (4,400 µg/kg). VOC’s. Finally, input of VOC’s to Lake Tahoe by subsur- face sources appears to be minor, at least in the areas investigated during this study. If a source such as this were present, VOC concentrations would be higher during the 1 ng/kg is an abbreviation for nanograms per kilogram winter because the source would not be seasonally depen- (equivalent to parts per trillion) and is equal to 0.001 µg/kg. dent.

10 Concentrations and Distribution of Manmade Organic Compounds in the Lake Tahoe Basin, Nevada and California, 1997-99 Soluble pesticides were not commonly detected dur- (site 14), a popular water skiing location, the highest com- ing this study, although, low concentrations were found in bined concentration of PAH’s and the most number of two water samples collected from tributary streams during compounds were found. Using the model of Huckins and spring runoff (table 3). No lake sample had a detectable others (1990), the concentration for fluoranthene is concentration of any pesticide. approximately 0.3 ng/kg. Samples from open water on Organochlorine compounds are synthetic com- Lake Tahoe (site 5), where motorized boating activity is pounds mostly used as insecticides, fungicides, and wood low, had a low number of compounds and combined con- preservatives. Organochlorine compounds were found in centrations of PAH’s. At this site (site 5), a sample from all SPMD and most bottom-sediment samples collected a depth of 36 m had lower combined concentration of during this study. Although present, the concentration of PAH’s than a sample from a depth of 3 m. Temporal vari- these compounds in the water column is less than one part ation in PAH concentrations within Lake Tahoe are not per trillion (as calculated using the model developed by presently known. PAH’s were not detected in bottom- Huckins and others, 1990). Chlordane (cis- and trans- sediment samples from Lake Tahoe, indicating little to isomers) and p,p’–DDE were found in all SPMD samples no accumulation of these compounds on the sediment. collected from Lake Tahoe. Chlordane and p,p’-DDT PAH’s were present in most SPMD samples from tributary (which degrades into p,p’-DDE) were commonly used streams in the Lake Tahoe Basin. Most of the samples had insecticides prior to the 1960’s and 1970’s. The use of between two and four compounds, two samples had no these specific compounds was discontinued by the mid- compounds, and the sample from Upper Truckee River 1970’s due to their effect on the environment, but, due to (site 6s) had seven compounds (fig. 4). Most streams, their persistence, they are still present. In Lake Tahoe, except Upper Truckee River, had higher combined con- SPMD samples near urbanized parts of the Lake (sites 1, centrations and number of compounds during the spring 11, and 13) had the highest concentration and number of runoff period than during the baseflow period. Actual con- organochlorine compounds suggesting their source may centrations of PAH’s in the water column generally are be urban areas. Hexachlorobenzene also was detected in less than 1 ng/kg (as calculated using the model developed four samples with the highest concentrations being in by Huckins and others, 1990). Upper Angora Lake, where samples offshore from Incline Beach and Edgewood no motorized boating occurs, had the fewest number of Creek (sites 1 and 11), both offshore from relatively dense compounds and lowest combined concentration of PAH’s, urban development. SPMD samples from the open-water indicating atmospheric sources are not the major input site (site 5) and Upper Angora Lake (site 17) had the low- into Lake Tahoe Basin lakes (fig. 2). Controlled burning of est concentrations of all lake samples. Bottom-sediment vegetation within the Lake Tahoe Basin may be a potential samples from Lake Tahoe had few detectable organochlo- source of PAH’s but appears to be a minor contribution. rine compounds with the exception of p-cresol, which was detected at every site, except site 1. A common ingredient in wood-preservative formulations, p-cresol probably is present in many of the treated piers and pilings in Lake Tahoe. Concentrations of organochlorine compounds in SPMD samples from tributary streams were similar to that from the open-water site in Lake Tahoe. Bottom-sediment samples collected from tributary streams had few detect- able concentrations of organochlorine compounds indi- cating they are not a current source for most of the compounds found in Lake Tahoe. PAH compounds are produced by high-temperature pyrolytic reactions such as in internal combustion engines, forest fires, and municipal incineration. Their occurrence in aquatic systems is reportedly due to anthro- pogenic sources (Smith and others, 1988). PAH’s were detected in all SPMD samples from Lake Tahoe. Concen- trations generally were higher in samples from Lake Tahoe than those from tributary streams. Nearshore sam- ples had the largest number of compounds and highest combined concentrations of PAH’s. PAH’s are most abun- dant in areas where the amount of motorized boating Sampling Taylor Creek, Nev., May 1998. Photograph by activity is high (sites 1 and 14). Offshore from Kiva Beach M.S. Lico, U.S. Geological Survey.

Discussion of Results 11 References Cited Huckins, J.N., Tubergen, M.W., and Manuweera, G.K., 1990, Semipermeable membrane devices containing Bevans, H.E., Goodbred, S.L., Miesner, J.F., Watkins, S.A., model lipid—A new approach to monitoring the bio- Gross, T.S., Denslow, N.D., and Schoeb, Trenton, 1996, availability of lipophilic contaminants and estimating Synthetic organic compounds and carp endocrinology their bioconcentration potential: Chemosphere, v. 20, and histology in Las Vegas Wash and Las Vegas and no. 5, p. 533-552. 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12 Concentrations and Distribution of Manmade Organic Compounds in the Lake Tahoe Basin, Nevada and California, 1997-99